The role of mitochondrial "tyrosine aminotransferase" in tyrosine metaboliam will be explored. Tyrosine-2- H3 and tyrosine -1 C14 will be substrates from evaluation of the contribution, if any, that the mitochondrial enzyme activity makes in the metabolism of tyrosine. The metabolism of DOPA via the transaminase pathway will be pursued further. We plan to examine the site of formation of 2,4,5- trihydroxphenylacetate (6-OH DOPAC) hoping to relate tissue location of the enzyme, P-hydroxyphenylpyruvate hydroxylase with formation of product. An estimation of the amount of DOP which proceeds through this pathway is also proposed. We shall include in this study, an investigation of the metabolism of 3-methoxy tyrosin via the transaminase pathway.